SiteInspector is a free, open-source tool that helps to find spelling errors, grammatical errors, and broken links on websites. The tool can be deployed using Docker or Heroku in less than 5 minutes.
SEMRush - All-in-one Marketing Toolkit for digital marketing professionals.
SEO Site Checkup - Find comprehensive search engine optimization (SEO) tools for your site.
Sitechecker - All-in-one SEO platform including rank tracker, website SEO audit tool and website changes monitoring. Detailed reports by 100+ parameters with how-to-fix guides.
SiteCheckerTool.com - Website Analytics & Tools
Screaming Frog SEO Spider - The Screaming Frog SEO Spider is a small desktop program (PC or Mac) which crawls websites’ links...
WebsiteChecker - Sends you alerts when your website goes down.